Visualizing Type-II Weyl Points in Tungsten Ditelluride by Quasiparticle Interference
Visualizing Type-II Weyl Points in Tungsten Ditelluride by Quasiparticle Interference
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DOI：
10.1021/acsnano.7b06179
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发表时间：
2017-11-01
期刊：
影响因子：
17.1
通讯作者：
Takagi, Noriaki
中科院分区：
文献类型：
--
作者：
Lin, Chun-Liang;Arafune, Ryuichi;Takagi, Noriaki
外尔半金属（Weyl semimetals，WSM）根据外尔点（Weyl point）的拓扑结构分为两类，第一类和第二类。二碲化钨（WTe2）作为II型WSM的有力候选者而引起了广泛关注。然而，WTe2的外尔点位于费米能级之上，这使我们无法通过使用角分辨光电子能谱来识别费米弧表面态的位置和连接。在这里，我们提出了实验证明，WTe2是一个II型WSM。我们用低温扫描隧道显微镜测量了能量相关的准粒子干涉图样，揭示了Weyl点的位置及其与费米弧表面态的联系，与先前的理论预测一致。我们的研究结果为这个关键问题提供了答案，并激发了对WSM特征的进一步探索。
Weyl semimetals (WSMs) are classified into two types, type I and II, according to the topology of the Weyl point, where the electron and hole pockets touch each other. Tungsten ditelluride (WTe2) has garnered a great deal of attention as a strong candidate to be a type-II WSM. However, the Weyl points for WTe2 are located above the Fermi level, which has prevented us from identifying the locations and the connection to the Fermi arc surface states by using angle-resolved photoemission spectroscopy. Here, we present experimental proof that WTe2 is a type-II WSM. We measured energy-dependent quasiparticle interference patterns with a cryogenic scanning tunneling Microscope, revealing the position of the Weyl point and its connection with the Fermi arc surface states, in agreement with prior theoretical predictions. Our results provide an answer to this crucial question and stimulate further exploration of the characteristics of WSMs.